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Insulin-like growth factor-I (IGF-I) is a survival factor for preimplantation mammalian embryos exposed to stress. One stress that compromises preimplantation embryonic development is elevated temperature (i.e., heat shock). Using bovine embryos produced in vitro as a model, it was hypothesized that IGF-I would protect preimplantation embryos by reducing(More)
Experiments were conducted to determine whether or not glutathione (GSH) is involved in thermotolerance responses of murine morulae. In the first experiment, morulae were exposed to either homeothermic temperature (37 degrees C), mild heat shock (40 degrees C for 1 h), severe heat shock (43 degrees C for 2 h), or a mild heat shock followed by severe heat(More)
A study was undertaken to determine the relationship between chromosome composition and embryo development. Bovine cumulus-oocyte complexes were matured in vitro and exposed to semen from one of three different bulls, one of which was a 1/29 Robertsonian translocation carrier. There were no significant differences among the three bulls in their sperm(More)
In three experiments, we tested the efficacy of timed artificial insemination (AI) and beta-carotene supplementation for improvement of reproduction and milk yield. Experiments 1 and 2 were conducted during hot months, and Experiment 3 was conducted during cooler months. Cows were fed rations supplemented with beta-carotene at 0 or 400 mg/d per cow for > or(More)
Experiments tested whether supplemental antioxidants improved fertility. To test effects of beta-carotene, cows in a hot environment were injected with prostaglandin F2 alpha (PGF2 alpha) and were given 3 injections, i.m., of 800 mg beta-carotene or saline at Days -6 and -3 before the anticipated date of insemination and at insemination (n = 37-41(More)
During their separate evolution from Bos taurus, zebu cattle (Bos indicus) have acquired genes that confer thermotolerance at the physiological and cellular levels. Cattle from zebu breeds are better able to regulate body temperature in response to heat stress than are cattle from a variety of B. taurus breeds of European origin. Moreover, exposure to(More)
PROBLEM Mastitis and immunization against constituents of organisms causing mastitis can reduce fertility of cattle and sheep, respectively. For the current experiments, it was hypothesized that these effects are mediated via actions of lipopolysaccharide (LPS), prostaglandin F2alpha (PGF2), and nitric oxide on oocyte maturation and embryonic development.(More)
The objective of this study was to determine whether bovine embryos become more resistant to deleterious effects of maternal heat stress as early embryonic development progresses. Superovulated, lactating Holstein cows were bred by AI and assigned to be heat stressed on d 1, 3, 5, or 7 of pregnancy (d 0 = day of estrus) or not heat stressed (control).(More)
Causes for pre-implantation embryo loss, which can be as high as 50% or more of fertilized embryos, are multifactorial and largely undescribed. Studies in cattle using mastitis as a model indicate that one cause of early embryonic loss is infectious disease or activation of immune responses at sites outside the reproductive tract. Infection of the mammary(More)
The objectives of this study were to determine whether the addition of growth hormone (GH) to maturation medium and GH or insulin-like growth factor-I (IGF-I) to culture medium affects development of cultured bovine embryos. We matured groups of 10 cumulus-oocyte complexes (COCs) in serum-free TCM-199 medium containing FSH and estradiol with or without 100(More)